chore: add notification action

[skip ci]

.github/actions/notify/action.yaml

@@ -0,0 +1,106 @@
+name: Send pull request notification to Google Chat
+description: |
+  Sends a notification to a Google Chat room when a pull request is opened.
+
+inputs:
+  title:
+    description: "The title of the notification."
+    required: true
+    default: 'no title provided'
+
+  event_author:
+    description: "The author of the event."
+    required: true
+    default: 'unknown'
+
+  event_title:
+    description: "The title of the event."
+    required: true
+
+  event_body:
+    description: "The body of the event."
+    required: true
+    default: 'no body provided'
+
+  event_number:
+    description: "The number of the event."
+    required: true
+    default: 'no number provided'
+
+  event_url:
+    description: "The url of the event."
+    required: true
+    default: 'none'
+
+
+runs:
+  using: "composite"
+  steps:
+    - name: Install prerequisites
+      shell: bash
+      run: apk add --no-cache curl jq
+
+    - name: Send PR notification to Google Chat
+      shell: bash
+      run: |
+        set -e
+
+        PAYLOAD=$(jq -n \
+          --arg repo "${{ github.repository }}" \
+          --arg title "${{ inputs.event_title }}" \
+          --arg body "${{ inputs.event_body }}" \
+          --arg author "${{ inputs.event_author }}" \
+          --arg url "${{ inputs.event_url }}" \
+          '{
+            "header": {
+              "title": "${{ inputs.title }}",
+              "subtitle": "Repo: \($repo)",
+              "imageUrl": "https://cdn.jsdelivr.net/gh/homarr-labs/dashboard-icons/png/git.png",
+              "imageType": "SQUARE"
+            },
+            "sections": [
+              {
+                "header": $title,
+                "collapsible": false,
+                "widgets": [
+                  {
+                    "decoratedText": {
+                      "icon": {
+                        "knownIcon": "PERSON"
+                      },
+                      "text": "<b>Opened by:</b> \($author)"
+                    }
+                  },
+                  {
+                    "textParagraph": {
+                      "text": $body,
+                      "maxLines": 2
+                    }
+                  }
+                ]
+              },
+              {
+                "widgets": [
+                  {
+                    "buttonList": {
+                      "buttons": [
+                        {
+                          "text": "View Source Event",
+                          "type": "FILLED",
+                          "onClick": {
+                            "openLink": {
+                              "url": $url
+                            }
+                          }
+                        }
+                      ]
+                    }
+                  }
+                ]
+              }
+            ]
+          }')
+
+        curl --fail-with-body -X POST -H 'Content-Type: application/json' \
+          "${{ secrets.GOOGLE_WEBHOOK_URL }}&messageReplyOption=REPLY_MESSAGE_FALLBACK_TO_NEW_THREAD&threadKey=${REPO}/pr/${PR_NUMBER}" \
+          -d "$(jq -n --argjson card "$PAYLOAD" '{ "cardsV2": [ { "cardId": "new-pr", "card": $card } ] }')"